How much HP is left on the table...

Hi guys, I'm kind of new to the FI world and I'm excited to get my hands dirty with the new car. I just came from tuning and driving a 9 second Mopar Big Block with a carb, so forgive me with the question;
I just picked up an 02 WS6. I've driven it a bit on the street and it has nice manners. But, the appeal of getting a more agressive tune is eating at me. The car has:
Stock heads
MS3 cam with topend kit
Hooker 1 7/8" Long tubes
Meziere water pump
No power steering
No AC
Rattler damper/pulley

The car is an M6 with a Currie 9" and a 3.90 Detroit Locker. I have a dyno sheet showing 401hp at the wheels. I was told it was a fairly conservative tune, but am wondering how much potential is left.